Corrugator steam system



Sepo 13, 1960 R..F. HOLLIS coRRuGAToR STEAM SYSTEM 3 Sheets-Sheet l Filed May 23, 1957 Sept. 13, 1960 R F HOLLIS 2,952,297

CORRUGATOR STEAM SYSTEM Filed May 23, 1957 3 Sheets-Sheet 2 y ZV 4./

Sept. 13, 1960 R. F. HOLLIS 2,952,297

CORRUGTOR` STEAM SYSTEM Filed May 23, 1957 @Sheets-Sheet 3 nted States Patent G CORRUGATOR STEAM SYSTEM Robert F. Hollis, Alton, lll., assignor to Alton Box Board Company, Alton, Ill., a corporation of Delaware Filed May 23, 1957, Sel'. No. 661,076

4 Claims. (Cl. 154-3105) This invention relates to the corrugation of paperboard, and in particular to a steam system for a corrugating unit.

It has been common practice heretofore to supply steam direct toYsteam showers, preheaters, glue stations and double facers at pressures in the range of about 125 to 200 pounds per square inch gauge (p.s.i.g.), which produces a temperature of less than 400 F. in the corrugator rolls. At pressures less than 125 p.s.i.g., the double facer oven plates have functioned imperfectly or not at all, as a practical matter. It has also beenconsidered desirable from the point of view of steam economy to use a minimum of steam in excess of the condensation [load so as to prevent the return to the boiler through the condensate return line of uncondensed steam with consequential slamming and pounding of these lines. As corrugating speeds have increased, the problems of obtaining high heat efciencyand nicety of control have increased. To a large extent, the two problems have been antithetical.

One of the objects of this invention is to provide a steam system for a corrugating unit which admits of more exact control and which is more uniformly eicient than steam systems known heretofore.

Other objects will become apparent to those skilled in the art in the light of the following disclosure and accompanying drawing.

In accordance with this invention, generally stated, I have discovered that by sweeping a large excess of steam, over and above `that required by the condensation load, through the various elements, by equipping the corrugator rolls and preheaters with restricters and traps, by venting traps and flash tanks to vent non-condensible gases at each major station so as to ensure removal of such gases at every stage in the unit, by returning the condensate to the boiler or boilers under pressure and at a correspondingly elevated temperature, by putting a plurality of oven plate sections in tandem and maintaining a substantial pressure differential between the last unit of the tandem series and the rst unit so as to ensure a steady sweep of steam through the system, by using diiferential pressure orifices in steam lines between oven plate sections to maintain predetermined ranges of differential pressure between oven plate sections, and by eliminating all restrictions in the discharge lines from the oven plates of the double facer to flash tanks, the diiiiculties with the steam systems known heretofore can be eliminated with a considerable economy of steam and very quick response to control settings. This is an unexpected result in that the increased flow of steam and the thorough venting of the system would appear to entail the use of more steam than has been used heretofore in conventional systems.

I have al-so `discovered that in using the system of my invention, far higher boiler pressures may be used than have been contemplated heretofore. The preferred range of steam pressureused in my system at the corrugatorrolls, is 300 to 600 pounds, with a steam tem- 2,952,297 Patented Sept. 13, 1960 ICC perature of between 420 and 490 F. and a roll tooth `temperature between approximately 415 and 480 F. although lower pressures have been successfully used. The steam pressure on the oven plates, on the other hand, may be as low as 30 pounds when light board is being run, with an adequate sweep of steam being maintained, and condensate continuously removed.

The arrangement of traps, flash tanks and differential valves is such as to permit accurate control of the temperature of the various elements.

In the drawing,

Figure 1 is a diagrammatic view of a steam system in accordance with one illustrative embodiment of this invention;

Figure 2 is a somewhat diagrammatic isometric view of the single facer units and boilers of a corrugator steam system in accordance with another illustrative ernbodiment of this invention; and

Figure 3 is a somewhat diagrammatic isometric View of the double facer portion of the steam corrugator system shown in Figure 2.

Referring now to Figure l of the drawing, a diagrammatic view of one illustrative embodiment of this invention, reference number 1 indicates `a corrugator made up of one single facer 3 and a double facer 4. The double facer 4 has a glue station 5 and an oven 7. The oven 7 is made up of a series of steam chest or plates which by way of illustration are divided into a rst unit 8 of ten chests, a second unit 9 of eight chests, a third unit 10 of seven chests, and a fourth unit 11 of three chests.

The glue station 5 is provided with a single face board preheater 20, and liner preheaters 21, 22 and 23.

The single facer 3 has an upper corrugator roll 12, a lower corrugator roll 13, a pressure roll 14 and an open shower 15. The single facer 3 also has the usual preheaters, indicated at 16.

In the illustrative embodiment shown, two boilers are used, a main boiler 140, yand a high pressure boiler 40. The high pressure boiler 40 supplies steam through a line 41 to a lirst steam supply header 42, at from 300 to 600 p.s.i.g. The first supply header 42 is connected by steam lines to the upper corrugator roll 12, the lower corrugator roll 13, and the pressure roll 14 of the single facer 3. The steam is discharged from 'the rolls l2, 13 and 14 through adjustable regulators (Stickles orifices) y43, 44 and l45 respectively, thence to a irst discharge header 46 connected through a pipe with a rst ash tank 50. The flash tanks referred to herein are in the nature of steam separators. The first ash tank 50 is equipped with a non-condensible gas vent 51, and a thermometer 52. The condensate in the flash tank 50 passes through a blast trap 53 into a condensate return pipe to a nal receiver 60. The steam from the flash tank 50 passes through a line 55, through a differenti-al controller 56, to a main steam line 47 from the main boiler 140. The pressure in the line 47 is normally not more than about 200 p.s.i.g.

From the main steam line 47, the steam flows through a line 48 to the preheaters 16 and through a line 49 and header, to the preheaters 20', 21, 22 and 23. A differential controller 63 is positioned in the line 47 between -the lines 48 and 49. Each of the preheaters is trapped individually with blast traps. From the blast traps, the steam and condensate from preheaters 16 pass, to a discharge header 61, and from preheaters 20, 21, 22 and 23 to a discharge header 62. From the discharge header 61 the steam and condensate pass to a second flash tank 70, which is also equipped with a non-condensible gas vent and a thermometer. From the discharge header 62, the steam and condensate pass to a third flash tank 75.

The condensate from the second flash tank 70 passes through a blast trap 73, through a condensate return pipe 54, to the final receiver 60. The steam fiashing in liash tank 70, and that uncondensed steam which passes through the preheaters 16 to the flash tank 70, passes, through a line 71, to the main steam line 47, on the same side of the differential controller 63 as the line 49'.

The condensate from lthe third fiash tank 75 passes through a blast trap 76 to the condensate line 54, thence to the final receiver 60. The steam flashing in flash tank 75, and that uncondensed steam which passes through the preheaters 20, 21, 22 and 23, passes, through a line 72, to the first unit 8 of the oven 7, which unit consists of ten steam chests connected ink parallel. The chests are connected to discharge to a common line through which the steam and condensate pass to a fourth fiash tank 80. It is to be noted that there are no restrictors in the lines from the chests to the fiash tank 80. The condensate in the fourth flash tank 80 passes through a blast trap 83 to the common condensate return line 54, thence to the final receiver 60. The steam which flashes in the fourth fiash tank 80 and the uncondensed steam which passes through the chests of the section 8, pass through a line 67, in which there is a restrictor 68, from the ash tank 80 to the next section 9 of eight chests, which are also connected in parallel with one another. The steam and condensate from the chests of section 9 pass unrestrictedly through a common line to a fifth flash tank 90. The condensate from the fifth flash tank 90 passes through a blast trap 93 to the common condensate return line 54, thence to the final receiver 60. The steam which flashes in Ithe fiash tank 90 and the uncondensed steam which passes through the chests of section 9 pass from the fiash tank 90 through a line 91, in which there is a restrictor 69, to the third section 10 of seven chests connected in parallel. The steam and condensate from the chests of section 10 pass unrestrictedly through a common line to a sixth flash tank 100. The condensate from the sixth fiash tank 100 passes through a blast trap 103 to the common co-ndensate return line 54, thence to the final receiver 60.

The steam which flashes in the fiash tank 100 and the uncondensed steam which passes through the chests of section 10 passes through a line 101, in which there is a restrictor 102, to the fourth section 11 of three chests connected in parallel. The steam and condensate from the chests of section '11 pass unrestrictedly through a common line to a seventh flash tank 110. The condensate from the seventh ash tank 110 passes through a blast trap 113 to the common condensate line 54, thence to the final receiver 60. The steam which fiashes in the flash tank 110 and the uncondensed steam which passes through the chests of section 11 passes through a line 111 to the final receiver 60. A differential controller 116 is positioned in the line 111.

From the final receiver 60, uncondensed steam from flash tank 110 and steam which fiashes in the receiver is delivered to the shower 15 through a line 117. A bypass line 118 from the flash tank 110 to the line 117 is arranged, with valves 114 yand 119, to enable steam to be sent to the shower 15 directly from the flash tank 110.

The condensate from the final receiver 60 is pumped to a feedwater tank for the two boilers, a pump 120 pumping to a feedwater tank 124 of the main boiler 140, and a pump 125 pumping to a feedwater tank 126 of the high pressure boiler 40.

Each of the blast traps 53, 73, 76, S3, 93, 103 and 113 is provided with an internal check valve. Each of the fiash tanks 50, 70, 75, 80, 90, 100 and `110, the final receiver 60, and the feed water tanks 124 and 126, is equipped with a non-condensible gas vent and a thermometer.

Each of the differential pressure controllers 56, 63 and 116 should be precisely calibrated and regulatable, in

order to realize the full benet of the system of this invention. In steam systems known heretofore, the steam pressures have been practically unregulable within wide limits, and simple spring-loaded differential valves have been sucient. With the present system, accurately regulated differential valves, controlled by air pressure or the like, can and must be used to give the nicety of control to which the system is capable of respending.

There are no traps or restrictors in any of the discharge lines from the chests in the sections 8, 9, 10 and 11, the steam passing freely through the chest to the ash tanks.

In the operation of the embodiment of corrugating system shown in Figure 1, steam is supplied from the high pressure boiler 40 to the corrugator rolls 12, 13 and 14 of the single facer 3, at from 300 to 600 p.s.i.g., going in to the header. The fiow of steam through the corrugator rolls of the single facer 3 is regulated by the adjustable orifices 43, 44, and 45. Since the steam and condensate from the cormgator rolls goes to the liash tank 50, and since the flash tank 50 is connected through the differential controller 55 -to the steam line 47 in which the pressure is on the order of 200 p.s.i.g., and to the final receiver 60, which is at even lower pressure than the steam line 47, a copious flow of steam is maintained through the single facer rolls. The differential controller 63 in the main steam line 47 between the line 48, leading to the preheaters for the single facer, and the line 49, leading to the glue station preheaters, provides a sufficient differential to permit steady fiow of steam from the flash tank 70 to the steam line 47 between the differential controller 63 and the line 49.

The steam and condensate from the glue station preheater rolls 20, 21, 22 and 23 goes to the ash tank 75.

The steam from the flash tank 75 goes directly to the v first section 8 of the oven 7. The ten chests of the first section 8 are connected in parallel, and their discharge lines are connected to a common header from which the steam and -condensate pass without restriction to the ash tank 80. It is to be noted that there is no restriction in the steam line between the flash tank 75 and the flash tank 80. The steam from the flash tank 75 thus sweeps through the first section 8 and into the flash tank 80 without restriction. In the line 67 between the flash tank S0 and the second section 9 of the oven 7, in which there are eight chests, there Iis a restrictor 68. This restrictor is preferably fixed. For example, if the line 67 is made up of 21/2 inch pipe, the restrictor 68 may take the form of a short length of one inch pipe. Between the restrictor 68 and the fiash tank 90 there are no restrictions in the system, so that the steam leaving the restrictor 68 makes an unrestricted sweep through the eight chests of the oven section 9. The steam from the liash tank passes through the line 91, in which the second restrictor 69 is positioned, to the third section 10 of the oven 7. The second restrictor 69 is also preferably fixed, and, if the line 91 is also of 21/2 inch pipe, may take the form of a short length of 7/s inch pipe. Between the restrictor 69 and the ash tank 100, the steam sweeps unrestrictedly through the seven chests making up the third oven section. Another 21/2 inch line 101 carries the steam which flashes from the flash tank to the fourth section 11 of three chests. The restrictor 102 in the line 101 may take the form of a section of Mt inch pipe. Between the restrictor 102 and the flash tank 110, there is no other restriction. The restrictors 68, 69 and 102 are designed to provide a differential between the chests of about four pounds, when no board is being processed. This differential arises from the ow of steam produced by the radiation losses from the chest and lines, even when the showers 15 are turned off. The restrictions produce -a differential of 6 to 8 pounds when board is being processed.

The concept of placing restrictors in the steam lines to the oven sections and no restriction in the discharge lines from the oven sections is a novel one, and the provision of such a system has several marked advantages. Since there is no restriction between the chests of a section and the flash tank associated with each chest section, the chests are swept clean of condensate. Since noncondensible gases are vented at each flash tank, the steam going to leach successi-'ve section has been freshly purged of non-condensible gases and such gases are neither accumulated in the system nor blocked in the chests by restrictors in the discharge lines. An important consequence of putting restrictors in the steam supply lines immediately between the flash tanks and the chest sections, is a slight superheating of the steam immediately before it reaches the chests. This comes about because there is a drop in pressure iat a constant total heat or enthalpy at this point. This superheating assists in preventing water logging, or slamming in the pipe system.

As a result of this system of restricting the discharge of the high pressure corrugator rolls, so that the supply of steam to the oven system is not Itotally uncontrolled, and the elimination of restriction on the discharge side of the oven sections and the restriction of the steam supply lines to oven sections, and of the venting of noncondensible gases at the discharge side of each major station, and each oven section, steam pressures as low as 30 p.s.i.g. at the last section have successfully been used with the system of this invention. This is to be compared with minimum pressures of around 125 p.s.i.g. in commercial systems known heretofore. In practice, the system of this invention h-as maintained the entire corrugator in ready condition, with the various rolls and chests in immediate condition to produce corrugated board, with the showers cut off entirely. A further advantage lies in the rapidity with which the corrugator can be brought to operative condition after a shutdown. This is accomplished by the `rapid flow of steam through the system and by the numerous non-condensible gas vents.

In Figures 2 and 3, a somewhat diagrammatic isometric view is shown of an embodiment of steam system of this invention which ldiffers in some respects from the embodiment shown in Figure 1, but which operates in substantially the same way. In this embodiment, as far as possible, the elements corresponding to elements of the embodiment shown in Figure l will be given the same reference numbers increased by 300.

In the embodiment shown in Figures 2 and 3, two single facers 303 and 303' are provided.

A double facer 304 has aglue station 305 and an oven 307. The oven 307 is made up of a series of steam chests which, in this embodiment, are divided into a irst unit 308 of nine chests, a second unit 309 of seven chests, a third unit 310 of six chests and a fourth unit 31=1 of three chests, only one of which, partly broken away, is shown.

The glue station 305 is provided with a single face board preheater 320 and linear preheaters 321 and 322.

The single facets 303 and 303', are provided with upper corrugator rolls 312 and 312', lower corrugator rolls 313 and 313 and pressure rolls 314 and 314 respectively. r[he single facer 303 has a liner preheater 316, a quadrant 416 and a medium preheater 516. The single facer 303 has a liner preheater 316', a second preheater 416', a third preheater 616' and a medium preheater 516. The single facers 303 and 303' are equipped with showers 315 and 315 respectively.

Two boilers are used, a main boiler 440 and a high pressure Iboiler, which may be a sto-called Bessler boiler, 340. The high pressure boiler 340 supplies steam through a high pressure line 341 to the single facer rolls 312, 313, 314, 312', 313', and 314' through high pressure headers 342 and 342', respectively. Discharge lines from the single facer rolls lead to Stickles orifices 343, 344 and 345, 3'43', 344', and 345', respectively, thence to discharge headers 346 and 346'. Froi the discharge headers 346 and 346' the steam and condensate are piped to a flash tank 350. 'Ihe flash tank 350 is equipped with Aa non-condensible gas vent 351 and a thermometer 352. The condensate from the flash tank 350 passes through a blast trap 353 to a common return line 354 which'leads to a final receiver 360. 'Ihe steam from the flash tank 350 passes through a line 355, through a differential controller 356 to a main steam line 347, leading from the main boiler 440.

A line 348 leads from the vmain steam line 347 to a header 448, from which steam is supplied to the preheater 316, 416 and 516 of the single facer station 303. A line 348' leads from the line 355, between the differential controllers 356 and the main steam line 347, to a header 448', fnom which steam is supplied to the preheaters 316', 416', 516 and 616' of the single facer station 303'.

Steam and condensate from the preheaters 316, 416 and 516 pass through discharge lines to individual blast traps 716. Steam and condensate from the preheaters 316', 416', 516' and 616 pass through discharge lines to individual blast traps 716'. The separate blast traps 716 and 716 discharge into common headers 361 and 361', respectively, which in turn are connectedl with a second flash tank 370, which is also equipped with a non-condensible gas Vent and a thermometer.

The condensate from the second ilash tank 370 passes through a blast trap 373 to the common condensate return line 354. The steam from flash tank 370 passes through a line 371 to a gluer header 449, which is also connected to the main steam line 347, in which there is a valve, so that the supplemental steam can be supplied from the main steam line 347, and the system can be brought to operating condition more quickly after a shutdown. Steam lines from the header 449 supply the preheater rolls 320, 321 and 322. In addition, a line from the header 449 runs directly to the first section 308 of the oven 307. Discharge lines from the preheaters 320, 321 and 322 lead to blast traps 323, which discharge into a common discharge header 362.

As shown in Figure 3, the chests of each oven section are connected in parallel both to their steam supply lines and their discharge lines. The discharge line from the first oven section 308 leads to a third flash tank 380. The header 362, in this embodiment, also is connected to discharge to the ii-ash tank 380. The flash tank 380 is equipped with a non-condensible gas vent and a thermometer. 'I'he condensate from the flash tank 380 is discharged through a blast trap 383 to the common condensate line 354. The steam from the flash tank 380 passes through a line 367 in which there is a restrictor 368, to the second section 309 of the oven 307. The chests of the section 309 discharge into a common line connected to a flash tank 390. The condensate from the flash tank 390 passes'through a blast trap 393 t0 the common condensate return line 354. The steam from the flash tank 390 is conducted through a line 391, in

which there is :a restrictor 369, to the third oven section 310. From the third oven section 310, the steam and condensate pass through a discharge line to a fifth flash tank 400. Condensate from the flash tank 400, passes through a blast trap 403 to the common condensate return line 354. The steam from the ilash tank 400 is conducted through ya line 401 in which there is a restrictor 402, to the fourth oven section 311. Steam and condensate from the fourth oven section 311 pass through a discharge pipe to a final flash tank 410. Condensate from the flash tank 410 passes through a blast trap 413 to the condensate return line 354. Steam from the flash tank 410 passes through a line 411 to the final receiver 360. A diferential controller 412 is in the line 14121 between the final flash tank 410 Iand the final receiver 360.

As indicated on the drawing, each of the flash tanks and final receiver is equipped with a non-condensible gas vent and thermometer.

A high pressure boiler condensate return pump 425 is connected in a line 426 between the final receiver 360 tand a feed water tank for the high pressure boiler 340. A main boiler condensate return pump A420 is in a line 421 between the final receiver 360 and a feed water tank for the main boiler 440.

The operation of the embodiment shown in Figures 2 and 3 is substantially the same as that described in the system shown in Figure 1. The chief differences in the systems lie in the supplying of steam from the header 449, in parallel to the glue station preheaters and the first chest section of the oven, yand the discharge of the glue station preheater rolls to the ash tank from which steam is lead to the second loven section. There is, in this embodiment, no provision for sending steam from the final flash tank direct to the showers. The shower steam is supplied from the final receiver 360 through a shower line 417 from the final receiver 360.

It can be seen that the system of this invention provides numerous advantages over the systems known heretofore. High corrugator roll temperatures can be maintained, but the flow of steam through these rolls to the main steam line can be accurately controlled by adjusting the orifices in their discharge lines. Relatively low pressure steam may be used on the oven sections with relatively high efiiciencies, as compared with systems known heretofore, because of the purging of the noncondensible gases from the system at each station, the unrestricted sweeping of the steam through the chests to the Trash tank associated with each section, and the super-heating of the steam by means of the restrictors in the steam supply lines.

While a two-boiler system is illustrated, a single boiler may be used, with suitable differential pressure valves. The system of this invention can be operated with low pressure steam at the single facer, but the use of high pressure steam permits high speed operation.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. In a corrugator steam system in which board passes successively through a single facer having corrugato-r rolls and a double facer having an oven made up ot -a multiplici-ty of team chests, wherein steam is supplied to the corrugator rolls and steam chests, the improvement comv prising dividing the said steam chests into a multiplicity of sections, said sections being connected to a steam supply in series with one another, a discharge line from the first section of the series running directly, without intermediate restriction, to a liash tank, `a steam line from said flash tank to the second section of the series, said steam line having a restrictor in it whereby a pressure drop is produced in the said steam line between the flash tank and the second section, said second section and each succeeding section having a discharge line running directly, without intermediate restriction, to -a flash tank and each of said flash tanks except the final one having a steam line to the neX-t succeeding section, each of said steam lines hav-- ing a restriction in it.

2. In a corrugator steam system in which -board passes successively through a single facer having preheaters and E corrugator rolls Vand a double facer having preheaters and an oven made up of a multiplicity of steam chests, wherein steam is supplied to the corrugator and preheater'rolls yand steam chests through ste-am lines, and condensate and uncondensed steam is discharged from them through discharge lines, the improvement comprising dividing the steam chests into a multiplicity of sections, said sections being connected in series with one another to a steam supply, providing restriction in the `discharge lines from the corrugatorvrolls and preheaters, said discharge lines being connected to flash tanks and said fiash tanks being connected by steam lines to the steam supply to the oven steam chests; providing no restrictions in the discharge lines from the oven steam chest section to a flash tank associated with each section, and providing a restriction in the steam supply line between each successive chest section.

3. In the process -o corrugating paperboard, wherein board is run successively through a single facer having preheaters and a double `facer having preheaters and an oven having a multiplicity of steam chests divided into a multiplicity of sections connected in series, wherein steam -is supplied to the preheaters and corrugator rolls and condensate and uncondensed steam is discharged from the preheaters and corrugator rolls toflash tanks, steam from said iiash tanks is supplied to the oven sections and each oven section is connected to discharge to a ash tank, the improvement comprising restricting the discharge from the prcheaters and coirrugator rolls to the flash tanks, sweeping the steam unrestrictedly through the oven chests of each section to its iiash tank, and restricting the flow of steam in the steam supply lines between successive oven sections.

4. in the process of corrugating paperboard, wherein board is run successively through a single facer having preheaters and a dou-ble facer having preheaters and an oven having a multiplicity of steam chests divided into a multiplicity of sections connected in series, wherein steam is supplied to the preheaters and corrugator rolls and condensate and uncondensed ste-am is discharged -from the preheaters `and corrugator rolls to iiash tanks, steam from said fiash tanks is supplied to the oven sections and each oven section is connected to discharge to a flash tank, the improvement comprising restricting the discharge from the preheaters and corrugator rolls to the flash tanks', :sweeping the steam unrestrictedy through the oven chests of each section to its tiash tank, restricting the fiow of steam in the steam supply lines between successive oven sections, and venting non-condensible gases `from each flash tank in the system.

References Cited in the lile of this patent UNITED STATES PATENTS 971,177 Dexter Sept, 27, 1910 1,503,679 Witham Aug. 5, 1924 1,817,110 Stickle Aug. 4, 1931 2,341,335 Simmons Feb. 8, 1944 2,487,647 Goettsch Nov. 8, 1949 FOREIGN PATENTS 608,125 Germany Ian. 16, 1935 

